In sound systems, there is some acoustic coupling between a loud speaker, an amplifier, and a microphone so that the entire system forms a closed loop. If a feedback ratio, or “loop gain,” exceeds a certain threshold, the system will oscillate, or “ring,” and acoustic feedback will occur. This feedback will persist until something is done to reduce the loop gain.
Many sound systems rely on an operator who can determine the presence of acoustic feedback and react before the resonance builds and becomes alarming to the audience, or before equipment damage takes place. The operator normally either reduces the system gain, or manually applies some filtering at a resonant frequency using an equalization device.
The role played by the operator in maintaining system stability against feedback would not be necessary if the system had the ability to detect its own feedback and upon detection, to reduce the loop gain of the system at that particular frequency until the ringing ceased. Accordingly, there is a need for a system or method that can detect the presence of acoustic feedback and automatically reduce the gain at a particular frequency or frequencies.